COACHES always prefer to make changes because they want to rather than because they have to, but for Declan Kidney there is now no such luxury.
Between injury, suspension and a frustratingly poor performance against England, the case for change is overwhelming. As things stand, there will be at least five alterations for the Scotland game, with Simon Zebo, Jonny Sexton, Mike McCarthy, Cian Healy and, yesterday, Gordon D'Arcy all ruled out.
The loss of any front-ranking player is inconvenient at the best of times, but injury to your pivotal playmaker mid-tournament is particularly so.
Anyone who has ever suffered hamstring damage will understand the painful nature of Sexton's injury and the time it takes to heal.
Of course, so much depends on the extent of the tear but from personal experience you can't test a hamstring's recovery in training – it can only be tested by the intensity of a competitive game.
The last thing Sexton, Leinster, Ireland and the Lions need is more serious damage to the muscle. Nature must be allowed to take its course.
There are, of course, more serious long-term ailments, but damage to the hamstring and to the rib cartilage were the areas that I always found most troubling as a player.
Of course, one man's injury is another man's opportunity, and Kidney, Les Kiss and the rest will be running a fine tooth-comb over the credentials of the four possible alternatives up until the team's announcement next week.
In reverse order Ian Keatley, Ian Madigan, Paddy Jackson and Ronan O'Gara will be the names in the frame.
The problem for Keatley and Madigan is that both play second fiddle to the main men (O'Gara and Sexton) at Munster and Leinster, respectively.
Lack of regular game time is a major issue for players stepping up to the Six Nations.
Jackson has pretty much established himself as the first-choice No 10 in a successful Ulster side but is still in the early days of his development.
It's not the age issue that concerns – if you're good enough you're old enough in my book; rather that Jackson may yet lack the required presence and conviction to play at Test level in such a pivotal position.
The impression is still of an out-half dependant on scrum-half Ruan Pienaar and his centres to nurse him along.
His Ulster role right now seems to be more 'link' than 'game manager' or 'decision maker'.
With experience, he should grow into a real general, but pitching a highly promising player into the cauldron that will be Murrayfield (on the back of the Italian win) is not worth the risk at this point in time for individual or team.
The difficulty for Kidney and his management is in assessing the relevance of the victory over Fiji (non-Test international) in Limerick back in November, when Jackson stood out alongside Cave, Luke Marshall, Craig Gilroy and Iain Henderson as the new Ulster kids on the block.
They certainly made the step up successfully that day, but the Fijians were abysmal.
Both Keatley and Madigan have proved substantial replacements for O'Gara and Sexton when required at provincial level.
Of the two, Madigan is marginally ahead on potential for promotion.
Next season should see both more regularly in situ, which will make individual assessment much easier.
I see the out-half decision as a no-brainer.
O'Gara is no longer the player he was, a fact he finds difficult to accept – which is no bad thing.
It's amazing how easily rugby folk – and particularly those outside Munster – choose to forget just how tactically astute and effective at the highest levels he was and can still be.
What I would like to see at this stage of a remarkable career is a little less tension in his body language and on-field demeanour – perhaps even the occasional smile wouldn't go amiss.
If he is looking for the ideal role-model with the ideal attitude (for one also in the twilight of a magnificent career), then his eyes need wander no further than the man he greatly admires just two positions out, Brian O'Driscoll.
If I were in his shoes, I would be lapping up this chance for what is a heaven-sent opportunity to continue to exert his influence at the highest level.
At times you get the impression his glass is at best half full, whereas in turning 36 in a few weeks' time, the attitude should be 'glass overflowing'.
Put simply, ROG, seize the day.
As for the replacement out-half to travel to Edinburgh, much will depend on the make-up of the rest of the backline (which I will discuss in detail before the team announcement on Wednesday).
Kidney might not agree but the pecking order to replace Sexton should read O'Gara, Madigan, Jackson and Keatley.
O'Gara might not prove the most popular replacement, but in terms of ticking boxes for what it takes to win on the road following defeat, he is the most realistic.
When you've lost as disappointingly as Ireland did to England, the last thing you need is change or experimentation in search of popularity.
Kidney's future will be back on the line should we come unstuck in Murrayfield.
With at least four changes in personnel already guaranteed, continuity in selection is essential at this point in the campaign.
If O'Gara was good enough to make the bench to face the English, then he is good enough to take a starting position in place of the injured Sexton.
Sometimes needs must and with victory an imperative for Kidney at Murrayfield, he must make the right decision.